Facebook apps on iPhones are pictured as Scott Forstall, senior vice president of iOS Software at Apple Inc.(not pictured) discusses deeper integration of the social media site in iOS6 during the Apple Worldwide Developers Conference 2012 in San Francisco, California June 11, 2012. (Photo : Reuters)

Until now, any Facebook user could send a message to any other Facebook user. After the company introduced actual email address (username@facebook.com), anyone could send an email to a Facebook account, even if they hadn't signed up for the service themselves.

And Facebook's new Messenger feature makes it even easier, slowly moving Facebook messages closer to a replacement for email.

But the open access system resulted in a lot of spam, so Facebook began filtering messages from outside a recipient's friend group (messages neither from a friend or a friend of a friend) into a dark pit called the Other folder, where messages go to die.

Many Facebook users had no idea it existed, and therefore never check it, so woe to the message caught by the filter. And goodbye Facebook flirting with random strangers.

But now Facebook is testing out a program that lets some users send messages to people they don't know for a small fee.

"This test will give a small number of people the option to pay to have a message routed to the Inbox rather than the Other folder of a recipient that they are not connected with," said Facebook in a blog post.

"Several commentators and researchers have noted that imposing a financial cost on the sender may be the most effective way to discourage unwanted messages and facilitate delivery of messages that are relevant and useful," said the blog. It also might bump up Facebook's profits.

For now, only individuals can use the pay-to-send feature, so corporations won't be carpet-bombing inboxes with advertisements just yet.

And the feature is currently limited to one message per week, so it really is just a test for now.

The filtering features for the Other inbox are also changing-to Basic and Strict.

"If you select Basic Filtering, you'll see mostly messages from friends and people you may know (for example, friends of friends) in your Inbox. People who had the previous setting set to "friends of friends" or "everyone" will have Basic Filtering on." Said Facebook.

"If you select Strict Filtering, you'll see mostly messages from friends in your Inbox. People who had the previous setting set to "friends" will have "Strict Filtering" on," the post continues.

Ideally the changes will make it easier for desirable messages to make it through the filters, while preventing a sudden influx of spam. Time will tell.